Magnetic tape cassette

ABSTRACT

A magnetic tape cassette includes an ID board for enabling a hardware to identify the magnetic tape by bringing contacts on a circuit board of the ID board which are exposed through an opening formed in a lower cassette half into contact with corresponding contacts in the hardware. Additionally, a plating treatment is provided on the contacts on the ID board. Further, a determined distance is secured between all end portions of the parts of the circuit board. Which are provided with the plating treatment, and the end faces of the circuit board. In an illustrative, non-limiting embodiment, the determined distance of the ID boards at a forward position in a moving direction of the magnetic tape cassette at which the contacts on the ID board are adapted to slidably contact with the contacts in the hardware is set to be 0.05-0.25 mm.

TECHNICAL FIELD

The present invention relates to a magnetic tape cassette such as adigital video cassette (DVC) or the like.

BACKGROUND OF THE INVENTION

Generally, in an audio apparatus, a video apparatus and the like, thereare in many cases used magnetic tape cassettes of a structure that amagnetic tape wound around a pair of tape reels is held inside acassette case so as to run for conducting recording and reproducing.

FIG. 12 is an exploded perspective view of the DVC which is one exampleof the magnetic tape cassette. The magnetic tape cassette 50 comprisesan upper cassette half 2 and a lower cassette half 3 each of which has aflat plate and peripheral walls. These upper and lower cassette halves2, 3 are assembled and fastened by means of a plurality of screws. Apair of tape reels 1 which are formed by welding their upper flangeswith their lower flanges are rotatably supported in the lower cassettehalf 3 in a state where a magnetic tape 47 is wound around the tapereels 1.

There are provided tape guides 14 at both sides of an opening 5 which isformed at a front end side (a lower side in the drawing) of the lowercassette half 3. Each of the tape guides 14 is adapted to guide themagnetic tape 47 which is fed from one of the tape reels 1 and taken upby the other tape reel and to pass the magnetic tape 47 at a determinedposition corresponding to the opening 5.

A tape reel locking member 16 having a tape reel locking arm 15 isassembled to a rear end side (an upper side in the drawing) of the lowercassette half 3. The tape reel locking member 16 is biased by means of acompression coil spring 17 so as to engage the tape reel locking arm 15with an engaging tooth which is formed at an outer circumference of thelower flange of each of the tape reels 1 thereby to block an accidentalrotation of the tape reel 1. A slackened winding of the magnetic tape 47can be prevented with this arrangement.

To the flat plate 4 of the upper cassette half 2 are fitted reelpressing leaf springs 48 for the respective tape reels 1. Each of thereel pressing leaf springs 48 is supported by the upper cassette half 2in a cantilever manner so as to push the corresponding tape reel 1toward the lower cassette half 3. Further, the flat plate 4 of the uppercassette half 2 is provided with an opening which extends in atransverse direction of the flat plate 4 at one side of the flat plate 4in its longitudinal direction (a right hand in the drawing) so that anamount of winding of the magnetic tape 47 on the tape reels 1 can beconfirmed. A transparent window member 49 is fitted so as to close theopening.

To a front end side of the upper cassette half 2 are freely and openablyfitted an outer lid 20, a top lid 21 and an inner lid 22 for covering afront and a back faces of the magnetic tape 47 which is stretchedbetween a pair of the tape guides 14 in the lower cassette half 3, inorder to obtain such a dust proofing property as durable for an outdooruse.

FIG. 13 shows one of the tape guides 14 which are provided in the lowercassette half 3 and shown in FIG. 12. Generally, the tape guide isuprightly provided on the flat plate of the lower cassette half. In thiscase, a hollow, that is, cylindrically formed tape guide 14 isintegrally formed on the flat plate 10 of the lower cassette half 3. Thetape guide 14 includes a curved portion 30 with which the magnetic tape47 slidably contacts, and flat portions 31 a, 31 b at a rear end side(an upper side in the drawing) and at an inner side (a left hand in thedrawing) of the tape guide respectively with which the magnetic tape 47does not contact. In this case, the tape guide 14 is formed in such amanner that a thickness of the tape guide 14 is substantially constantin a circumferential direction, and therefore, the curved portion 30 andthe flat portions 31 a, 31 b are substantially equal to each other inthickness.

When the lower cassette half 3 is formed by molding, a molten resinintroduced into a mold fills at first a cavity for the flat plate 10.Then, the molten resin flows into cavities for the tape guides 14connected to the cavity for the flat plate 10 and into cavities forother members.

There has been sometimes formed a weld line (hereinafter referred to as“a weld”) W on a surface of the curved portion 30 of the tape guide 14as shown in FIG. 14, when the lower cassette half 3 of the abovedescribed magnetic tape cassette 50 is molded. In addition, a pock v ofan air bubble which is generated when the air bubble is discharged hasbeen also formed in some cases on the surface of the curved portion 30.There is a fear that such a weld W or an air bubble pock v may damagethe magnetic tape if they are formed on the surface of the curvedportion 30 with which the magnetic tape slidably contacts.

The term “weld” means herein a thin line which is formed at a portionwhere two or more streams of the molten resin join, and the term “airbubble” means a hollow spot which is formed inside a molded article.

A first object of the invention is to provide a magnetic tape cassettewhich is free from molding defects on the surface of the curved portionof the tape guide with which the magnetic tape slidably contacts.

FIG. 15 shows a manner of placing the window member 49 on the flat plate4 so as to close the opening formed in the flat plate 4, when the windowmember 49 shown in FIG. 12 is welded to the flat plate 4 of the uppercassette half 2. As shown in FIG. 15, this work is generally conductedby hand.

An inner face (an upper face in the drawing) of the flat plate 4 of theupper cassette half 2 is formed at a peripheral part of the opening witha stepped flat face 35 a (hereinafter referred to as “a windowsupporting face”) which is recessed from other parts of the inner faceof the flat plate. The window supporting face 35 a supports theperipheral edge of the window member 49, when the window member 49 isplaced on the flat plate 4. A side face 35 b between the inner face ofthe flat plate 4 and the window supporting face 35 a is formed in atapered shape which serves as an introducing face for guiding the windowmember 49 to the window supporting face 35 a.

FIG. 16 shows a sectional view taken along a line Y—Y in FIG. 15 in astate where the window member 49 has been placed on the flat plate 4. Asshown in FIG. 16, a peripheral wall (a back end wall) 7 of the uppercassette half 2 is provided at its outer face with a recess 7 a to whicha label is to be attached. A peripheral edge of the window member 49 isarranged close to an inner face of a base portion of the peripheral wall7.

A part of an outer face (a lower face in the drawing) of the windowmember 49 which is supported by the window supporting face 35 a is in aform of a stepped flat face 49 a (hereinafter referred to as “asupported face”) which is recessed from other parts of the outer face ofthe window member. The supported face 49 a is projectingly provided witha welded rib 49 b in a shape of a triangle in section, which is adaptedto abut against the window supporting face 35 a of the flat plate 4 whenthe window member 49 is placed on the flat plate 4.

FIG. 17 shows another upper cassette half 52 which has beenconventionally used. The flat plate 4 of the upper cassette half 52,similarly to the upper cassette half 2 shown in FIG. 16, has the windowsupporting face 35 a, and the side face 35 b connecting the inner faceof the flat plate to the window supporting face 35 a is formed in atapered face. A positioning rib 45 having a side face which is verticalwith respect to the inner face of the flat plate is formed at the innerface of the base portion of the peripheral wall 7. In such an uppercassette half 52, the window member 49 can be accurately positioned onthe flat plate 4 without affecting its mountability, by preciselyforming the side face of the positioning rib 45.

In order to weld the window member 49 to the flat plate 4 of the uppercassette half 2 as shown in FIG. 16, when the window member 49 is placedon the flat plate 4 and released from the hand, the window member 49sometimes adheres to the hand by static electricity, etc. and floats upfrom the flat plate 4, as shown by a two-dot chain line in FIG. 18. Incase where the window member 49 is released from the hand in the air, anaccurate positioning of the window member 49 on the flat plate 4 may besometimes impossible, so that the supported face 49 a of the windowmember may ride on the inner face of the flat plate, as shown by a solidline in FIG. 18, for example.

Also in case where the window member 49 is placed on the flat plate 4 ofthe upper cassette half 52 as shown in FIG. 17, when the window member49 is released from the hand, the window member sometimes adheres to thehand and floats up from the flat plate 4 as shown by a two-dot chainline in FIG. 19. When the window member 49 is released from the hand inthe air, the supported face 49 a of the window member may sometimes tideon the upper face of the positioning rib 45 as shown by a solid line inFIG. 19.

As described above, the work for accurately positioning the windowmember 49 on the flat plate 4 has been very annoying, and an improvementof the work has been required.

A second object of the invention is to provide a magnetic tape cassettein which the window member can be easily placed on an accurate positionof the flat plate, when the window member is fitted to the flat plate ofthe upper cassette half.

As shown in FIG. 20, at a corner part of the rear end wall 7 of theupper cassette half 2, is formed an opening 34 for exposing a safety lugfor preventing a wrong erasure of recorded data on the magnetic tape.Moreover, at a corner part of a rear end wall 11 of the lower cassettehalf 3 are formed openings 37 for exposing contacts of an ID board foridentifying a type and a use of the magnetic tape.

FIG. 21 is a plan view of the ID board. The ID board 33 has a pluralityof (four in FIG. 21) contacts 36 which are exposed through the openings37 formed in the lower cassette half. Signals concerning the type andthe use of the magnetic tape are exchanged between the ID board and arecording and reproducing apparatus (a hardware) by way of the contacts36. The ID board is manufactured through the following steps:

First of fall, a copper foil is applied to a printed circuit board 38formed of a substrate material such as a glass reinforced epoxy resin orthe like, and after a desired pattern has been printed (etched) on theboard, the copper foil is removed from unnecessary parts thereby to formthe copper foil of a desired shape (rectangular in FIG. 21) whichconstitutes the contacts 36. Then, after the printed circuit board 38 isrinsed, the copper foil is plated with gold. Plating the copper foilwith gold is an indispensable treatment for preventing a faultydetection due to repeated sliding motions of the ID board with respectto the hardware. Finally, by stamping by means of a stamping die, theprinted circuit board 38 is formed in such a desired shape (flat platelike and substantially L-shaped in FIG. 21) as the printed circuit board38 can be received in the lower cassette half.

There has been a problem that on occasion that the printed circuit board38 of ID board 33 is stamped on the stamping die, a minute burr 39 maybe created at an end face of each of the contacts 36 of the printedcircuit board 38 in a direction of an arrow B in FIG. 22, and partialdamages 40 or the like may be caused on the gold plating on the copperfoil by the burr 39. When the burr on the gold plating and the partialdamages 40 or the like have occurred, there has been a fear that whilethe magnetic tape cassette 50 is repeatedly inserted into and removedfrom the hardware 43 as shown in FIG. 23, the burrs may be spreadfurther to reach to an insulating part, or a broken piece may adhere tothe insulating part to cause a short of the printed circuit board 38.

A third object of the invention is to provide a magnetic tape cassettein which the partial damages of the plating on the contacts due to theminute burrs in the ID board can be reliably avoided, whereby a short ofthe circuit board of the ID board can be reliably prevented.

As shown in FIG. 12, the upper cassette half 2 of the magnetic tapecassette 50 includes the flat plate 4, the rear end wall 7, the frontend wall 6 having the opening 5, and a left and a right side walls 8which are positioned at outermost sides in a longitudinal direction ofthe upper cassette half 2. The lower cassette half 3 includes the flatplate 10, the rear end wall 11, the front end wall 13 having the opening5, and a left and a right side walls 12 which are positioned atoutermost sides in a longitudinal direction of the lower cassette half3. The outer lid 20 includes a lid front face 23 and two lid side faces24. The top lid 21 includes a lid upper face 25 and two lid side faces26. The top lid 21 has an inner lid 22 rotatably fitted thereto.

FIG. 24 is a perspective view of an assembled product of the magnetictape cassette 50. FIG. 24A is an overall view of the assembled product,FIG. 24B is an enlarged view of an encircled part A in FIG. 24A.

FIG. 25 is a plan view of the assembled product of the magnetic tapecassette 50 as shown in FIG. 24. FIG. 25A is an overall view of theassembled product, and FIG. 25B is an enlarged view of an encircled partB in FIG. 25A.

Longitudinal dimensions of the outer lid 20 and the top lid 21 areslightly smaller than a longitudinal dimension of the cassette caseconsisting of the upper cassette half 2 and the lower cassette half 3assembled together. As shown in FIG. 25B, the end walls 8, 12 of thecassette case extend outwardly (leftward and rightward in FIG. 25)beyond the lid side faces 24, 26 in a longitudinal direction of thecassette case. They are thus designed so that the outer lid 20 and thetop lid 21 may not project beyond the side walls 8, 12 of the cassettecase, even though the outer lid 20 and the top lid 21 move in thelongitudinal direction to be displaced toward one side by an amount Diof the displacement, when the magnetic tape cassette 50 is loaded in thehardware. With this design, the loading of the magnetic tape cassette 50in the hardware can be smoothly conducted.

However, because the cassette case is so constructed as to project inthe longitudinal direction beyond the lids as described above, in casewhere a user unintentionally happens to load the cassette 50 inclinedlyin the hardware, front edges 28 of the projecting side walls 8, 12 ofthe cassette case may sometimes collide against a cassette loading mouthin the hardware. Moreover, when the cassette is forced to be loaded, thefront edges 28, the outer lid 20 and the inner lid 21 will be caughtinside the cassette loading mouth and can not be taken out of thehardware in the worst case.

A fourth object of the invention is to provide a magnetic tape cassettewhich can be smoothly loaded in the recording and reproducing apparatus,even in case where the user unintentionally happens to load the cassetteinclinedly in the recording and reproducing apparatus.

DISCLOSURE OF THE INVENTION

The inventors of the invention have earnestly studied and found out thatthe above described first object can be attained by making the thicknessof the curved portion of the tape guide larger than the thickness of theother parts such as the flat portions.

A magnetic tape cassette according to the invention comprises a lowercassette half having tape guides integrally formed therewith and anupper cassette half assembled to the upper cassette half to form acassette case, a pair of tape reels around which a magnetic tape iswound being rotatably supported inside the cassette case, the magnetictape being guided by the tape guides so as to run at a determinedposition, and is characterized in that each of the tape guides includesa cylindrical part having in its circumferential direction a curvedportion with which the magnetic tape slidably contacts, the curvedportion having a thickness larger than those of other circumferentialportions of the cylindrical part.

In the magnetic tape cassette of the above described structure, moldingdefects will not happen on a surface of the curved portion of the tapeguide, when the upper cassette half is molded.

Because the conventional tape guide has been formed in such a mannerthat the curved portion and the other portions such as the flat portionsare substantially equal to each other in thickness, the molten resin hasfilled the cavity for the flat portion first of all at molding, and thestreams of the molten resin flowed from both circumferential sides havesometimes joined in the cavity for the curved portion. In such case, thewelds or the like have been formed on the surface of the curved portionof the tape guide.

According to the invention, because the thickness of the curved portionis larger than the thickness of the other portions such as the flatportions, and the molten resin fills at first the cavity for the curvedportion which is wider and easier to receive the flow, and then fillsthe cavities for the flat portions. Accordingly two streams of the resinwill not join in the cavity for the curved portion so that occurrence ofthe welds or the like can be prevented.

According to the invention, the thickness of the curved portion of thetape guide may be larger than the thickness of the other portions incircumferential direction of the tape guide, and the thickness of thecurved portion is preferably one and a half (1.5) to three (3) times aslarge as the thickness of the other portions. With this design, theoccurrence of the molding defects on the surface of the curved portionwill be more remarkably prevented.

The second object of the invention can be attained by a magnetic tapecassette which comprises an upper cassette half having a flat plateprovided with a peripheral wall and an opening, a window member of aseparate body being fitted to the upper cassette so as to close theopening, and a lower cassette assembled to the upper cassette half toform a cassette case, a pair of tape reels around which a magnetic tapeis wound being rotatably supported inside the cassette case,characterized in that the peripheral wall is provided with a positioningrib which extends from a base portion of the peripheral wall up to aposition higher than a half of a height of the peripheral wall, thepositioning rib being adapted to abut against a part of acircumferential edge of the window member.

In case where the positioning rib does not extend up to the half of theheight of the peripheral wall from the base portion of the peripheralwall, the window member is likely to adhere to the hand and float upwhen the window member is released from the hand, and when the windowmember is released from the hand in the air, the window member will notbe placed at the accurate position on the flat plate in some cases.

In the magnetic tape cassette of the above described structure, when thewindow member is fitted to the flat plate of the upper cassette half,the window member can be easily placed at the accurate position on theflat plate.

In case where the window member is fitted to the upper cassette half ofthe magnetic tape cassette of the above described structure, when thewindow member is released from the hand after it has been placed on theflat plate, it is preferable to slide the fingers or the like which arein contact with the window member along the window member by withdrawingthe hand toward the peripheral wall which is provided with thepositioning rib. With this motion, the window member can be preventedfrom floating up from the flat plate.

The peripheral wall of the upper cassette half may be provided with aplurality of positioning ribs, but even a single positioning rib canfully achieve the function.

According to the invention, the height of the positioning rib is a halfor more of the height of the peripheral wall and the same or less as theheight of the peripheral wall. A difference in height between theperipheral wall and the positioning rib is preferably 2 mm or less. Withthis design, the window member can be more reliably placed at theaccurate position on the flat plate.

The third object of the invention can be attained by a magnetic tapecassette which comprises an ID board for enabling a hardware to identifythe magnetic tape by bringing contacts on a circuit board which isexposed through an opening formed in a lower cassette half into contactwith corresponding contacts in the hardware, characterized in that aplating treatment is provided on the contacts on the ID board, and thata determined distance is secured between all end portions of the partsprovided with the plating treatment and end faces of the circuit board.

In the magnetic tape cassette according to the invention, the ID boardenables the hardware to identify the type or the use of the magnetictape by bringing the contacts on the board exposed through an openingwhich is formed in the lower cassette half into contact with thecorresponding contacts in the hardware. The plating treatment isprovided on the contacts of the ID board. Because a determined distanceis secured between the end portions of the plated parts and the endfaces of the board, a stamping cutter will not abut against the platedparts when the board is stamped by means of a press. Accordingly, theburrs and damages will not be generated on the plated parts and shortsof the contacts by a metal piece can be prevented beforehand.

In this case, all the end portions of the plated parts means entireperipheral edges of the plated parts, and in case where the rectangularparts are plated as shown in FIG. 21, all the four edges of each therectangular part are meant. The end face of the board means a facearound the board which is substantially perpendicular to a direction ofa plane of the board.

From a view point of preventing the occurrence of the burrs which may bea cause of the shorts, the distance had better be as large as possible.However, as shown in FIG. 23, the magnetic tape cassette 50 is loaded inthe hardware 43 while the plated parts 36 of the ID board 33 are slid ina direction of an arrow C with respect to the corresponding contacts 44of the hardware. Accordingly, in case where the distance is too large,it may happen that the exposed parts of the ID board 33 (those parts notplated) will get to slidingly contact with the contacts 44 and areliable detection of the contact will be impossible. Therefore, thedistance at the forward end in the sliding direction of the arrow Camong these distances is preferably 0.25 mm or less in view ofelectrically stable detection of the contacts.

Meanwhile, having earnestly studied and examined the burrs or damages inquestion with respect to size, their sizes were found to be betweenabout 0.02-0.1 mm.

Therefore, considering stability of the above described contactdetection and variations in working precision, the distance at theforward end is 0.05-0.25 mm and preferably 0.1-0.15 mm.

The fourth object of the invention can be attained by a magnetic tapecassette which comprises a cassette case consisting of an upper and alower cassette halves, a pair of tape reels around which a magnetic tapecontained in the cassette case is wound, and an openable lid fitted tothe cassette case so as to cover an opening along which the magnetictape arranged at a front side of the cassette case is adapted to pass,characterized in that side faces of the cassette case are provided withcut away portions so that forward ends of the side faces of the cassettecase maybe always located closer to an inner space of the cassette casethan side faces of the openable lid.

According to the above described structure of the invention, even incase where the cassette is loaded in a cassette loading mouth with theopenable lid displaced toward one side and inclinedly with respect tothe cassette loading mouth, the cassette will not be caught and can besmoothly guided into the interior of the hardware, because the forwardends of the side faces of the cassette case may be always located closerto the inner space of the cassette case than the side faces of theopenable lid due to the presence of the cut away portions. Therefore,the magnetic tape cassette can be smoothly loaded in the hardware.

The cut away portion may be of a tapered or a curved shape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a magnetic tape cassette according to a firstembodiment of the invention.

FIG. 2 is a view showing a tape guide of a lower cassette half in FIG.1.

FIG. 3 is a plan view of the tape guide as shown in FIG. 2.

FIG. 4 is a view showing a state in which a window member is fitted toan upper cassette half of a magnetic tape cassette according to a secondembodiment of the invention.

FIG. 5 is a sectional view taken along a line Y—Y in FIG. 4 when thewindow member has been placed on the upper cassette half.

FIG. 6 is a view showing a state in which a finger is detached from thewindow member shown in FIG. 5.

FIG. 7 is a plan view showing a lower cassette half in a magnetic tapecassette according to a third embodiment of the invention.

FIG. 8 is a plan view showing an ID board of the magnetic tape cassettein FIG. 7.

FIG. 9 is an enlarged perspective view of an essential part of the IDboard in FIG. 8.

FIGS. 10A and 10B are a plan view of a magnetic tape cassette accordingto a fourth embodiment of the invention, and an enlarged plan view of anessential part of the magnetic tape cassette respectively.

FIGS. 11A, 11B and 11C are views showing a manner in which the magnetictape cassette is loaded in a cassette loading mouth of a hardware.

FIG. 12 is an exploded perspective view showing a conventional magnetictape cassette.

FIG. 13 is a view showing a tape guide of a lower cassette half in FIG.12.

FIG. 14 is a view showing the tape guide in which molding defects haveoccurred.

FIG. 15 is a view showing a manner in which a window member is fitted toan upper cassette half of the conventional magnetic tape cassette.

FIG. 16 is a sectional view taken along a line Y—Y in FIG. 15 when thewindow member has been placed on the upper cassette half.

FIG. 17 is a view showing a state in which the window member is placedon another conventional upper cassette half.

FIG. 18 is a view showing a state in which a finger is detached from thewindow member shown in FIG. 16.

FIG. 19 is a view showing a state in which a finger is detached from thewindow member shown in FIG. 17.

FIG. 20 is a perspective view showing the conventional magnetic tapecassette.

FIG. 21 is a plan view showing an ID board of the magnetic tape cassettein FIG. 20.

FIG. 22 is a perspective view of the ID board in FIG. 21, and anenlarged perspective view of an essential part thereof.

FIG. 23 is a sectional view of the magnetic tape cassette surroundingthe ID board when it has been loaded in the hardware.

FIGS. 24A and 24B are a perspective view of the conventional magnetictape cassette, and an enlarged perspective view of an essential partthereof respectively.

FIGS. 25A and 25B are a plan view of the conventional magnetic tapecassette, and an enlarged plan view of an essential part thereofrespectively.

FIG. 26 is a schematic plan view of the conventional magnetic tapecassette when a lid portion has been displaced.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, embodiments of the invention will be described in detail withreference to the drawings. Those members which have been alreadydescribed will be denoted with the same or equivalent reference numeralsand signs to simplify or omit a further explanation.

FIG. 1 shows a magnetic tape cassette according to a first embodiment ofthe invention. The magnetic tape cassette 100 comprises an uppercassette half 2 and a lower cassette half 103 assembled into a cassettecase, in which a pair of tape reels wound with a magnetic tape 47 arerotatably supported. In the magnetic tape cassette 100, the magnetictape 47 is guided by means of a pair of tape guides 114 which areintegrally formed with the lower cassette half 103 so that the magnetictape 47 can run at a determined position.

FIG. 2 shows one of the tape guide 114 provided in the lower cassettehalf 103 as shown in FIG. 1. The tape guide 114 in a cylindrical shapeis integrally formed with a flat plate 110 of the lower cassette half103. The tape guide 114 includes a curved portion 130 with which themagnetic tape 47 slidably contacts, a flat portion 131 a at a rear endside of the tape guide 114 (opposite to a side facing with a head of ahardware when the magnetic tape cassette is loaded in the hardware, thatis, an upper side in the drawing) with which the magnetic tape does notcontact, and a flat portion 131 b at an inner side of the tape guide(facing with the other tape guide, that is, on a left hand in thedrawing). One end of the flat portion 131 a and one end of the flatportion 131 b are in a right angle with each other when seen in a planview. The other end of the flat portion 131 a and the other end of theflat portion 131 b are connected by way of the curved portion 130 whichis composed of a curved face projecting outwardly in a radial direction.

In this embodiment, a thickness of the curved portion 130 of the tapeguide 114 is larger than those of the flat portions 131 a and 131 b.

FIG. 3 is a plan view of the tape guide 114 as shown in FIG. 2. In thetape guide 114 as shown in FIG. 3, the thickness T2 of the flat portion131 a at the rear end side of the tape guide is substantially the sameas the thickness T3 of the flat portion 131 a at the inner side of thetape guide. And the thickness T1 of the curved portion 130 is formedlarger than the thicknesses T2 and T3.

Though specific dimensions of the thicknesses vary depending on types ofthe magnetic tape cassettes, in a DVC of a larger size (an L size), forexample, it can be set that T1=0.8 mm, T2=T3=0.4 mm.

With the magnetic tape cassette 100 of the above described structure, amolten resin fills at first a cavity for the curved portion 130 which iswider and easier to receive a flow of the resin, and then, fillscavities for the flat portions 131 a, 131 b. Accordingly, two streams ofthe resin will not be joined to each other in the cavity for the curvedportion 130, so that molding defects such as welds or air bubbles willnot be generated on a surface of the curved portion 130 of the tapeguide 114.

It is to be noted that the magnetic tape cassette of the invention isnot limited to the above described embodiment, but appropriatemodifications and improvements are possible.

For example, the tape guide 114 is formed in a cylindrical shape alongits entire heights in the above described embodiment. However, the tapeguide 114 may have a solid part, or may be provided with a lid memberfor covering a distal end of the tape guide.

FIG. 4 shows a state in which a window member is placed on a flat plateof an upper cassette half in a second embodiment of the invention so asto close an opening formed in the flat plate when the window member iswelded to the upper cassette half. The flat plate 204 of the uppercassette half 202 is formed with a window supporting face 235 a at acircumferential edge of the opening. When the window member 49 has beenplaced on the flat plate 204, the window supporting face 235 a isadapted to support a circumferential edge of the window member 49. Inthis embodiment, a larger part of a side face 235 b which connects aninner face of the flat plate to the window supporting face 235 a isformed in a tapered face as an introducing face, except a part of theside face 235 b extending in a transverse direction of the uppercassette half 202 which is formed in a curved convex face 235 cperpendicular to the inner face of the flat plate so as to clamp thewindow member to position it at an accurate position.

Moreover, at an inner face (a face adjacent to a space inside thecassette case) of a peripheral wall (a rear end wall) 207 of the uppercassette half 11, is formed a positioning rib 255 which extends up to aheight more than a half of a height of the peripheral wall. In thisembodiment, a shape of the positioning rib 255 is semi-circular insection, but the shape is not particularly limited. The positioning ribhaving a triangular or other multangular shape in section can be alsoemployed.

FIG. 5 shows a sectional view taken along a line Y—Y in FIG. 4 when thewindow member 49 has been placed on the flat plate 204. As shown in FIG.5, at an outer face of the peripheral wall (the rear end wall) 207 ofthe upper cassette half 202, is formed a recessed portion 207 a to whicha label is to be attached. At an inner face of a base portion of theperipheral wall 207, a part of the circumferential edge of the windowmember 49 is abutted against a lateral face of the positioning rib 255so that the window member 49 maybe disposed at an accurate position onthe flat plate 204.

The lateral face of the positioning rib 255 is formed perpendicular tothe inner face of the flat plate. A difference H between the height ofthe peripheral wall 207 and the height of the positioning rib 255 is setto be 0.5 mm in this case.

When the window member 49 is released from the hand after it has beenpositioned at the accurate position, it is preferable to slide thefingers or the like which are in contact with the window member 49 alongthe window member 49 by withdrawing the hand toward the peripheral wall207 in a direction of an arrow A in the drawing. In this manner, a partof the circumferential edge of the window member 49 can be kept incontact with the positioning rib 27, and the window member 49 can beprevented from floating up from the flat plate 25.

When the window member 49 which has been once positioned at the accurateposition is caused to float in the air as shown in a two-dot chain linein FIG. 6, the supported face 49 a of the window member 49 will not rideon an upper face 255 a of the positioning rib 255. Because a part of thecircumferential edge of the window member 49 which has floated up iskept in contact with the lateral face of the positioning rib 255 in thisembodiment, the window member 49 can be released from the hand bywithdrawing the hand toward the peripheral wall 207 provided with thepositioning rib 255 in a direction of an arrow B in the drawing so as toslide the fingers which are in contact with the window member 49 alongthe window member 49. The window member 49 released from the hand isguided by the lateral face of the positioning rib 255 and placed againat the accurate position on the flat plate as shown in a solid line inFIG. 6.

In the magnetic tape cassette of the above described structure, thewindow member 49 can be easily placed at the accurate position on theflat plate 204 on occasion that the window member 49 is welded to theflat plate 204 of the upper cassette half 202.

Further, as compared with the upper cassette half in the conventionalmagnetic tape cassette, the magnetic tape cassette according to thisembodiment is modified only by providing a single thin positioning rib255 on the peripheral wall 207, and therefore, a structure of the moldwill not be complicated. Moreover, the molding defects such as a moldingsink, etc. will not be generated on the outer face of the peripheralwall.

It is to be noted that the magnetic tape cassette is not limited to theabove described embodiment, but appropriate modifications andimprovements are possible.

For example, the positioning rib 255 is provided on the rear end wall207 of the upper cassette half 202 in the above described embodiment,but the positioning rib may be provided on side walls or the like of theupper cassette half according to shapes, etc. of the window member andthe opening.

Moreover, though the window member 49 is placed by hand on the flatplate 204 of the upper cassette half 202 in the described embodiment, itis possible to carry out this work automatically.

FIG. 7 shows a lower cassette half according to the third embodiment ofthe invention. A magnetic tape cassette 300 comprises a pair of tapereels 1 (a tape reel at a right hand in the drawing is omitted to beillustrated) wound with a magnetic tape (not shown) which are rotatablysupported on a lower cassette half 3 which is in a pair with an uppercassette half (not shown). The lower cassette half 3 is integrallyformed of a synthetic resin such as an ABS resin or the like.

An ID board 333 for identifying a type and a use of the magnetic tape isprovided in the lower cassette half 3 at its lower corner part at aright hand in FIG. 7. The ID board 333 is located in the lower cassettehalf 3 at a position enclosed by a side wall 12 and a partition rib 19.

The ID board 333 has a plurality of (four in FIG. 8) contacts 336 a to336 d. These contacts 336 a to 336 d are exposed through an opening (notshown) formed at the corner of the lower cassette half, and signalsconcerning the type and use of the magnetic tape cassette will beexchanged with a recording and reproducing apparatus (a hardware) whichis not shown, by way of the contacts 336 a to 336 d.

Of the contacts 336 a to 336 d of the ID board 333, a first contact 336a located at the leftmost end in FIG. 8 acts for identifying a thicknessof the magnetic tape, a second contact 336 b located in a second placefrom the left in FIG. 8 acts for identifying the type of the magnetictape, a third contact 336 c located in a third place from the left inFIG. 8 acts for identifying the use of the magnetic tape, and a fourthcontact 336 d located at the rightmost end in FIG. 8 acts for grounding(GND).

In short, the thickness of the magnetic tape can be identified byreading a resistance value between the first contact 336 a and thefourth contact 336 d by means of the hardware. The type of the magnetictape can be identified by reading a resistance value between the secondcontact 336 b and the fourth contact 336 d by means of the hardware.Further, the use of the magnetic tape can be identified by reading aresistance value between the third contact 336 c and the fourth contact336 d by means of the hardware.

The above described ID board 333 is manufactured through the followingsteps:

First of all, a copper foil is applied to a printed circuit board 338formed of a substrate material such as a glass reinforced epoxy resin orthe like, and after a desired pattern has been printed (etched), thecopper foil on unnecessary parts is removed, thereby to form the copperfoil of a desired shape (rectangular in FIG. 8) on the printed circuitboard 338 which constitutes the contacts 336 a to 336 d. Then, rinsingthe printed circuit board 338, a plating treatment by gold is conductedon the copper foil. The plating treatment on the copper foil by goldwill prevent detection faults due to repeated sliding contacts with thehardware. The printed circuit board 338 is formed by a stamping work bymeans of a stamping die into a desired shape (flat plate like andsubstantially L-shaped as seen in a plan view in FIG. 8) which issuitable for enabling it to be contained in the lower cassette half.

As shown in FIG. 9, a determined distance A is maintained between endportions 356 (end portions adjacent to end faces of the board 338, alower and a right hand ends in the drawing) of the contact 336 d havingthe gold plating on the copper foil of the ID board 333 and end faces357 of the printed circuit board 338. In this embodiment, the distance Ais 0.1 mm. By thus maintaining the distance A, even in case where theminute burr 39 (refer to FIG. 22) is generated on the printed circuitboard 338 at the stamping work of the printed circuit board 338 by meansof the stamping die, the partial damage 40 or the like (refer to FIG.22) of the gold plating caused by the burr 39 will be reliablyprevented.

According to the above described embodiment, because the determineddistance A is maintained between the ends 356 of the gold plated part onthe copper foil of the ID board 333 and the end faces 357 of the printedcircuit board 338, even when the minute burr 39 is generated at thestamping work of the printed circuit board 338 by means of the stampingdie, the partial damage 40 or the like of the gold plating caused by theburr 39 will be reliably prevented. Accordingly, even in case where themagnetic tape 300 is repeatedly loaded in and unloaded from thehardware, the printed circuit board 338 can be reliably prevented fromshorts.

FIGS. 10A and 10B show a magnetic tape cassette according to the fourthembodiment of the invention. FIG. 10A is a plan view of the magnetictape cassette 400, and FIG. 10B is an enlarged view of an encircled partB in FIG. 10A.

The magnetic tape cassette 400 comprises a left and a right side walls408 which are located at the outermost positions of the upper cassettehalf 402 in a longitudinal direction of the cassette, and similarsidewalls 412 in the lower cassette half. Near forward ends 428 of sidefaces (outer faces) of the side walls 408, 412, there are formed cutaway portions 408 a, 412 a in a tapered shape which are oriented towardan inner space of the cassette-case as approaching to the forward end428. Of the cut away portions 408 a and 412 a, the forward ends 428 ofthe side walls which are the closest to the lids 24, 26 are so adaptedas to be always positioned inward of the left and the right lid sidefaces 24 of the outer lid 20 and the left and the right lid side faces26 of the top lid 21, as viewed in a longitudinal direction of thecassette case.

In other words, the forward ends 428 of the side faces of the side wallsare so adapted to be positioned closer to the inner space of thecassette case than the left and the right lid side faces 24, 26 of theouter lid 20 and the top lid 21.

Now, referring to FIG. 11, a manner in which the magnetic tape cassette400 is loaded into the hardware will be described.

FIGS. 11A to 11C show the manner in which the cassette 400 is loaded ina cassette loading mouth 60 of a deck when the lid is displaced to oneside at the maximum degree. As shown in FIG. 11A, at a beginning stageof the loading, the cassette 400 is going to be inserted inclinedly withrespect to the cassette loading mouth 60. On this occasion, the cut awayportions 408 a, 412 a are abutted against a corner 70 of the cassetteloading mouth 60. Proceeding the loading of the cassette 400 from thissituation, the cassette 400 is slightly rotated into a state as shown inFIG. 11B. Further proceeding the loading of the cassette 400, the cutaway portions 408 a, 412 a slide on the corner 70, and as a result, thecassette 400 is guided into an interior of the hardware as shown in FIG.11C.

As described above, even though the cassette 400 is loaded inclinedlywith respect to the hardware, the cassette 400 will not be caught by thehardware. Accordingly, it will not be the case that the cassette 400cannot be taken out of the hardware. On the other hand, in case wherethe cassette 400 is loaded into the cassette loading mouth 60 of thehardware in a slightly displaced state in a sideward direction, but notinclinedly, the cassette 400 can be smoothly loaded in the hardwarebecause the cut away portions 408 a, 412 a act as guiding members as inthe case where the cassette 400 is inclined.

The invention is not limited to the described embodiment, butappropriate modifications and improvements, etc. are possible. Forexample, the openable lid is not limited to the lid of three plate type,but may be of two plate type comprising a lid consisting of the outerlid and the top lid so referred to in this embodiment which areintegrally formed, and the inner lid. In addition, technical concepts ofthe invention can be applied to other magnetic tape cassettes than theDVC. Although the invention has been described on the basis of theseveral embodiments, it is apparent that this invention may comprisecombinations of at least two of these embodiments or modifications.

What is claimed is:
 1. A magnetic tape cassette which comprises an IDboard for enabling a hardware to identify said magnetic tape by bringingcontacts on a circuit board of said ID board which are exposed throughan opening formed in a lower cassette half into contact withcorresponding contacts in said hardware, wherein a plating treatment isprovided on said contacts on said ID board, and a determined distance issecured between all end portions of said parts provided with saidplating treatment and end faces of said circuit board, and wherein saiddistance of said ID board at a forward position in a moving direction ofsaid magnetic tape cassette at which said contacts on said ID board areadapted to slidably contact with said contacts in said hardware is setto be 0.05-0.25 mm.
 2. The magnetic tape cassette as claimed in claim 1,wherein the circuit board is formed into a desired shape by a stampingoperation using a stamping die.
 3. A magnetic tape cassette whichcomprises an ID board for enabling a hardware to identify said magnetictape by bringing contacts on a circuit board of said ID board which areexposed through an opening formed in a lower cassette half into contactwith corresponding contacts in said hardware, wherein a platingtreatment is provided on said contacts on said ID board, and adetermined distance is secured between all end portions of said partsprovided with said plating treatment and end faces of said circuitboard, and wherein said distance of said ID board at a forward positionin a moving direction of said magnetic tape cassette at which saidcontacts on said ID board are adapted to slidably contact with saidcontacts in said hardware is set to be 0.1-0.15 mm.
 4. The magnetic tapecassette as claimed in claim 3, wherein the circuit board is formed intoa desired shape by a stamping operation using a stamping die.